/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package android.animation;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.ViewTreeObserver;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.view.animation.DecelerateInterpolator;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.List;
/**
* This class enables automatic animations on layout changes in ViewGroup objects. To enable
* transitions for a layout container, create a LayoutTransition object and set it on any
* ViewGroup by calling {@link ViewGroup#setLayoutTransition(LayoutTransition)}. This will cause
* default animations to run whenever items are added to or removed from that container. To specify
* custom animations, use the {@link LayoutTransition#setAnimator(int, Animator)
* setAnimator()} method.
*
* <p>One of the core concepts of these transition animations is that there are two types of
* changes that cause the transition and four different animations that run because of
* those changes. The changes that trigger the transition are items being added to a container
* (referred to as an "appearing" transition) or removed from a container (also known as
* "disappearing"). Setting the visibility of views (between GONE and VISIBLE) will trigger
* the same add/remove logic. The animations that run due to those events are one that animates
* items being added, one that animates items being removed, and two that animate the other
* items in the container that change due to the add/remove occurrence. Users of
* the transition may want different animations for the changing items depending on whether
* they are changing due to an appearing or disappearing event, so there is one animation for
* each of these variations of the changing event. Most of the API of this class is concerned
* with setting up the basic properties of the animations used in these four situations,
* or with setting up custom animations for any or all of the four.</p>
*
* <p>By default, the DISAPPEARING animation begins immediately, as does the CHANGE_APPEARING
* animation. The other animations begin after a delay that is set to the default duration
* of the animations. This behavior facilitates a sequence of animations in transitions as
* follows: when an item is being added to a layout, the other children of that container will
* move first (thus creating space for the new item), then the appearing animation will run to
* animate the item being added. Conversely, when an item is removed from a container, the
* animation to remove it will run first, then the animations of the other children in the
* layout will run (closing the gap created in the layout when the item was removed). If this
* default choreography behavior is not desired, the {@link #setDuration(int, long)} and
* {@link #setStartDelay(int, long)} of any or all of the animations can be changed as
* appropriate.</p>
*
* <p>The animations specified for the transition, both the defaults and any custom animations
* set on the transition object, are templates only. That is, these animations exist to hold the
* basic animation properties, such as the duration, start delay, and properties being animated.
* But the actual target object, as well as the start and end values for those properties, are
* set automatically in the process of setting up the transition each time it runs. Each of the
* animations is cloned from the original copy and the clone is then populated with the dynamic
* values of the target being animated (such as one of the items in a layout container that is
* moving as a result of the layout event) as well as the values that are changing (such as the
* position and size of that object). The actual values that are pushed to each animation
* depends on what properties are specified for the animation. For example, the default
* CHANGE_APPEARING animation animates the <code>left</code>, <code>top</code>, <code>right</code>,
* <code>bottom</code>, <code>scrollX</code>, and <code>scrollY</code> properties.
* Values for these properties are updated with the pre- and post-layout
* values when the transition begins. Custom animations will be similarly populated with
* the target and values being animated, assuming they use ObjectAnimator objects with
* property names that are known on the target object.</p>
*
* <p>This class, and the associated XML flag for containers, animateLayoutChanges="true",
* provides a simple utility meant for automating changes in straightforward situations.
* Using LayoutTransition at multiple levels of a nested view hierarchy may not work due to the
* interrelationship of the various levels of layout. Also, a container that is being scrolled
* at the same time as items are being added or removed is probably not a good candidate for
* this utility, because the before/after locations calculated by LayoutTransition
* may not match the actual locations when the animations finish due to the container
* being scrolled as the animations are running. You can work around that
* particular issue by disabling the 'changing' animations by setting the CHANGE_APPEARING
* and CHANGE_DISAPPEARING animations to null, and setting the startDelay of the
* other animations appropriately.</p>
*/
public class LayoutTransition {
/**
* A flag indicating the animation that runs on those items that are changing
* due to a new item appearing in the container.
*/
public static final int CHANGE_APPEARING = 0;
/**
* A flag indicating the animation that runs on those items that are changing
* due to an item disappearing from the container.
*/
public static final int CHANGE_DISAPPEARING = 1;
/**
* A flag indicating the animation that runs on those items that are appearing
* in the container.
*/
public static final int APPEARING = 2;
/**
* A flag indicating the animation that runs on those items that are disappearing
* from the container.
*/
public static final int DISAPPEARING = 3;
/**
* These variables hold the animations that are currently used to run the transition effects.
* These animations are set to defaults, but can be changed to custom animations by
* calls to setAnimator().
*/
private Animator mDisappearingAnim = null;
private Animator mAppearingAnim = null;
private Animator mChangingAppearingAnim = null;
private Animator mChangingDisappearingAnim = null;
/**
* These are the default animations, defined in the constructor, that will be used
* unless the user specifies custom animations.
*/
private static ObjectAnimator defaultChangeIn;
private static ObjectAnimator defaultChangeOut;
private static ObjectAnimator defaultFadeIn;
private static ObjectAnimator defaultFadeOut;
/**
* The default duration used by all animations.
*/
private static long DEFAULT_DURATION = 300;
/**
* The durations of the four different animations
*/
private long mChangingAppearingDuration = DEFAULT_DURATION;
private long mChangingDisappearingDuration = DEFAULT_DURATION;
private long mAppearingDuration = DEFAULT_DURATION;
private long mDisappearingDuration = DEFAULT_DURATION;
/**
* The start delays of the four different animations. Note that the default behavior of
* the appearing item is the default duration, since it should wait for the items to move
* before fading it. Same for the changing animation when disappearing; it waits for the item
* to fade out before moving the other items.
*/
private long mAppearingDelay = DEFAULT_DURATION;
private long mDisappearingDelay = 0;
private long mChangingAppearingDelay = 0;
private long mChangingDisappearingDelay = DEFAULT_DURATION;
/**
* The inter-animation delays used on the two changing animations
*/
private long mChangingAppearingStagger = 0;
private long mChangingDisappearingStagger = 0;
/**
* The default interpolators used for the animations
*/
private TimeInterpolator mAppearingInterpolator = new AccelerateDecelerateInterpolator();
private TimeInterpolator mDisappearingInterpolator = new AccelerateDecelerateInterpolator();
private TimeInterpolator mChangingAppearingInterpolator = new DecelerateInterpolator();
private TimeInterpolator mChangingDisappearingInterpolator = new DecelerateInterpolator();
/**
* These hashmaps are used to store the animations that are currently running as part of
* the transition. The reason for this is that a further layout event should cause
* existing animations to stop where they are prior to starting new animations. So
* we cache all of the current animations in this map for possible cancellation on
* another layout event. LinkedHashMaps are used to preserve the order in which animations
* are inserted, so that we process events (such as setting up start values) in the same order.
*/
private final HashMap<View, Animator> pendingAnimations =
new HashMap<View, Animator>();
private final LinkedHashMap<View, Animator> currentChangingAnimations =
new LinkedHashMap<View, Animator>();
private final LinkedHashMap<View, Animator> currentAppearingAnimations =
new LinkedHashMap<View, Animator>();
private final LinkedHashMap<View, Animator> currentDisappearingAnimations =
new LinkedHashMap<View, Animator>();
/**
* This hashmap is used to track the listeners that have been added to the children of
* a container. When a layout change occurs, an animation is created for each View, so that
* the pre-layout values can be cached in that animation. Then a listener is added to the
* view to see whether the layout changes the bounds of that view. If so, the animation
* is set with the final values and then run. If not, the animation is not started. When
* the process of setting up and running all appropriate animations is done, we need to
* remove these listeners and clear out the map.
*/
private final HashMap<View, View.OnLayoutChangeListener> layoutChangeListenerMap =
new HashMap<View, View.OnLayoutChangeListener>();
/**
* Used to track the current delay being assigned to successive animations as they are
* started. This value is incremented for each new animation, then zeroed before the next
* transition begins.
*/
private long staggerDelay;
/**
* The set of listeners that should be notified when APPEARING/DISAPPEARING transitions
* start and end.
*/
private ArrayList<TransitionListener> mListeners;
/**
* Controls whether changing animations automatically animate the parent hierarchy as well.
* This behavior prevents artifacts when wrap_content layouts snap to the end state as the
* transition begins, causing visual glitches and clipping.
* Default value is true.
*/
private boolean mAnimateParentHierarchy = true;
/**
* Constructs a LayoutTransition object. By default, the object will listen to layout
* events on any ViewGroup that it is set on and will run default animations for each
* type of layout event.
*/
public LayoutTransition() {
if (defaultChangeIn == null) {
// "left" is just a placeholder; we'll put real properties/values in when needed
PropertyValuesHolder pvhLeft = PropertyValuesHolder.ofInt("left", 0, 1);
PropertyValuesHolder pvhTop = PropertyValuesHolder.ofInt("top", 0, 1);
PropertyValuesHolder pvhRight = PropertyValuesHolder.ofInt("right", 0, 1);
PropertyValuesHolder pvhBottom = PropertyValuesHolder.ofInt("bottom", 0, 1);
PropertyValuesHolder pvhScrollX = PropertyValuesHolder.ofInt("scrollX", 0, 1);
PropertyValuesHolder pvhScrollY = PropertyValuesHolder.ofInt("scrollY", 0, 1);
defaultChangeIn = ObjectAnimator.ofPropertyValuesHolder((Object)null,
pvhLeft, pvhTop, pvhRight, pvhBottom, pvhScrollX, pvhScrollY);
defaultChangeIn.setDuration(DEFAULT_DURATION);
defaultChangeIn.setStartDelay(mChangingAppearingDelay);
defaultChangeIn.setInterpolator(mChangingAppearingInterpolator);
defaultChangeOut = defaultChangeIn.clone();
defaultChangeOut.setStartDelay(mChangingDisappearingDelay);
defaultChangeOut.setInterpolator(mChangingDisappearingInterpolator);
defaultFadeIn = ObjectAnimator.ofFloat(null, "alpha", 0f, 1f);
defaultFadeIn.setDuration(DEFAULT_DURATION);
defaultFadeIn.setStartDelay(mAppearingDelay);
defaultFadeIn.setInterpolator(mAppearingInterpolator);
defaultFadeOut = ObjectAnimator.ofFloat(null, "alpha", 1f, 0f);
defaultFadeOut.setDuration(DEFAULT_DURATION);
defaultFadeOut.setStartDelay(mDisappearingDelay);
defaultFadeOut.setInterpolator(mDisappearingInterpolator);
}
mChangingAppearingAnim = defaultChangeIn;
mChangingDisappearingAnim = defaultChangeOut;
mAppearingAnim = defaultFadeIn;
mDisappearingAnim = defaultFadeOut;
}
/**
* Sets the duration to be used by all animations of this transition object. If you want to
* set the duration of just one of the animations in particular, use the
* {@link #setDuration(int, long)} method.
*
* @param duration The length of time, in milliseconds, that the transition animations
* should last.
*/
public void setDuration(long duration) {
mChangingAppearingDuration = duration;
mChangingDisappearingDuration = duration;
mAppearingDuration = duration;
mDisappearingDuration = duration;
}
/**
* Sets the start delay on one of the animation objects used by this transition. The
* <code>transitionType</code> parameter determines the animation whose start delay
* is being set.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose start
* delay is being set.
* @param delay The length of time, in milliseconds, to delay before starting the animation.
* @see Animator#setStartDelay(long)
*/
public void setStartDelay(int transitionType, long delay) {
switch (transitionType) {
case CHANGE_APPEARING:
mChangingAppearingDelay = delay;
break;
case CHANGE_DISAPPEARING:
mChangingDisappearingDelay = delay;
break;
case APPEARING:
mAppearingDelay = delay;
break;
case DISAPPEARING:
mDisappearingDelay = delay;
break;
}
}
/**
* Gets the start delay on one of the animation objects used by this transition. The
* <code>transitionType</code> parameter determines the animation whose start delay
* is returned.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose start
* delay is returned.
* @return long The start delay of the specified animation.
* @see Animator#getStartDelay()
*/
public long getStartDelay(int transitionType) {
switch (transitionType) {
case CHANGE_APPEARING:
return mChangingAppearingDuration;
case CHANGE_DISAPPEARING:
return mChangingDisappearingDuration;
case APPEARING:
return mAppearingDuration;
case DISAPPEARING:
return mDisappearingDuration;
}
// shouldn't reach here
return 0;
}
/**
* Sets the duration on one of the animation objects used by this transition. The
* <code>transitionType</code> parameter determines the animation whose duration
* is being set.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose
* duration is being set.
* @param duration The length of time, in milliseconds, that the specified animation should run.
* @see Animator#setDuration(long)
*/
public void setDuration(int transitionType, long duration) {
switch (transitionType) {
case CHANGE_APPEARING:
mChangingAppearingDuration = duration;
break;
case CHANGE_DISAPPEARING:
mChangingDisappearingDuration = duration;
break;
case APPEARING:
mAppearingDuration = duration;
break;
case DISAPPEARING:
mDisappearingDuration = duration;
break;
}
}
/**
* Gets the duration on one of the animation objects used by this transition. The
* <code>transitionType</code> parameter determines the animation whose duration
* is returned.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose
* duration is returned.
* @return long The duration of the specified animation.
* @see Animator#getDuration()
*/
public long getDuration(int transitionType) {
switch (transitionType) {
case CHANGE_APPEARING:
return mChangingAppearingDuration;
case CHANGE_DISAPPEARING:
return mChangingDisappearingDuration;
case APPEARING:
return mAppearingDuration;
case DISAPPEARING:
return mDisappearingDuration;
}
// shouldn't reach here
return 0;
}
/**
* Sets the length of time to delay between starting each animation during one of the
* CHANGE animations.
*
* @param transitionType A value of {@link #CHANGE_APPEARING} or @link #CHANGE_DISAPPEARING}.
* @param duration The length of time, in milliseconds, to delay before launching the next
* animation in the sequence.
*/
public void setStagger(int transitionType, long duration) {
switch (transitionType) {
case CHANGE_APPEARING:
mChangingAppearingStagger = duration;
break;
case CHANGE_DISAPPEARING:
mChangingDisappearingStagger = duration;
break;
// noop other cases
}
}
/**
* Tets the length of time to delay between starting each animation during one of the
* CHANGE animations.
*
* @param transitionType A value of {@link #CHANGE_APPEARING} or @link #CHANGE_DISAPPEARING}.
* @return long The length of time, in milliseconds, to delay before launching the next
* animation in the sequence.
*/
public long getStagger(int transitionType) {
switch (transitionType) {
case CHANGE_APPEARING:
return mChangingAppearingStagger;
case CHANGE_DISAPPEARING:
return mChangingDisappearingStagger;
}
// shouldn't reach here
return 0;
}
/**
* Sets the interpolator on one of the animation objects used by this transition. The
* <code>transitionType</code> parameter determines the animation whose interpolator
* is being set.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose
* duration is being set.
* @param interpolator The interpolator that the specified animation should use.
* @see Animator#setInterpolator(TimeInterpolator)
*/
public void setInterpolator(int transitionType, TimeInterpolator interpolator) {
switch (transitionType) {
case CHANGE_APPEARING:
mChangingAppearingInterpolator = interpolator;
break;
case CHANGE_DISAPPEARING:
mChangingDisappearingInterpolator = interpolator;
break;
case APPEARING:
mAppearingInterpolator = interpolator;
break;
case DISAPPEARING:
mDisappearingInterpolator = interpolator;
break;
}
}
/**
* Gets the interpolator on one of the animation objects used by this transition. The
* <code>transitionType</code> parameter determines the animation whose interpolator
* is returned.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose
* duration is being set.
* @return TimeInterpolator The interpolator that the specified animation uses.
* @see Animator#setInterpolator(TimeInterpolator)
*/
public TimeInterpolator getInterpolator(int transitionType) {
switch (transitionType) {
case CHANGE_APPEARING:
return mChangingAppearingInterpolator;
case CHANGE_DISAPPEARING:
return mChangingDisappearingInterpolator;
case APPEARING:
return mAppearingInterpolator;
case DISAPPEARING:
return mDisappearingInterpolator;
}
// shouldn't reach here
return null;
}
/**
* Sets the animation used during one of the transition types that may run. Any
* Animator object can be used, but to be most useful in the context of layout
* transitions, the animation should either be a ObjectAnimator or a AnimatorSet
* of animations including PropertyAnimators. Also, these ObjectAnimator objects
* should be able to get and set values on their target objects automatically. For
* example, a ObjectAnimator that animates the property "left" is able to set and get the
* <code>left</code> property from the View objects being animated by the layout
* transition. The transition works by setting target objects and properties
* dynamically, according to the pre- and post-layoout values of those objects, so
* having animations that can handle those properties appropriately will work best
* for custom animation. The dynamic setting of values is only the case for the
* CHANGE animations; the APPEARING and DISAPPEARING animations are simply run with
* the values they have.
*
* <p>It is also worth noting that any and all animations (and their underlying
* PropertyValuesHolder objects) will have their start and end values set according
* to the pre- and post-layout values. So, for example, a custom animation on "alpha"
* as the CHANGE_APPEARING animation will inherit the real value of alpha on the target
* object (presumably 1) as its starting and ending value when the animation begins.
* Animations which need to use values at the beginning and end that may not match the
* values queried when the transition begins may need to use a different mechanism
* than a standard ObjectAnimator object.</p>
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose
* duration is being set.
* @param animator The animation being assigned. A value of <code>null</code> means that no
* animation will be run for the specified transitionType.
*/
public void setAnimator(int transitionType, Animator animator) {
switch (transitionType) {
case CHANGE_APPEARING:
mChangingAppearingAnim = animator;
break;
case CHANGE_DISAPPEARING:
mChangingDisappearingAnim = animator;
break;
case APPEARING:
mAppearingAnim = animator;
break;
case DISAPPEARING:
mDisappearingAnim = animator;
break;
}
}
/**
* Gets the animation used during one of the transition types that may run.
*
* @param transitionType one of {@link #CHANGE_APPEARING}, {@link #CHANGE_DISAPPEARING},
* {@link #APPEARING}, or {@link #DISAPPEARING}, which determines the animation whose
* duration is being set.
* @return Animator The animation being used for the given transition type.
* @see #setAnimator(int, Animator)
*/
public Animator getAnimator(int transitionType) {
switch (transitionType) {
case CHANGE_APPEARING:
return mChangingAppearingAnim;
case CHANGE_DISAPPEARING:
return mChangingDisappearingAnim;
case APPEARING:
return mAppearingAnim;
case DISAPPEARING:
return mDisappearingAnim;
}
// shouldn't reach here
return null;
}
/**
* This function sets up animations on all of the views that change during layout.
* For every child in the parent, we create a change animation of the appropriate
* type (appearing or disappearing) and ask it to populate its start values from its
* target view. We add layout listeners to all child views and listen for changes. For
* those views that change, we populate the end values for those animations and start them.
* Animations are not run on unchanging views.
*
* @param parent The container which is undergoing an appearing or disappearing change.
* @param newView The view being added to or removed from the parent.
* @param changeReason A value of APPEARING or DISAPPEARING, indicating whether the
* transition is occuring because an item is being added to or removed from the parent.
*/
private void runChangeTransition(final ViewGroup parent, View newView, final int changeReason) {
Animator baseAnimator = (changeReason == APPEARING) ?
mChangingAppearingAnim : mChangingDisappearingAnim;
// If the animation is null, there's nothing to do
if (baseAnimator == null) {
return;
}
// reset the inter-animation delay, in case we use it later
staggerDelay = 0;
final long duration = (changeReason == APPEARING) ?
mChangingAppearingDuration : mChangingDisappearingDuration;
final ViewTreeObserver observer = parent.getViewTreeObserver(); // used for later cleanup
if (!observer.isAlive()) {
// If the observer's not in a good state, skip the transition
return;
}
int numChildren = parent.getChildCount();
for (int i = 0; i < numChildren; ++i) {
final View child = parent.getChildAt(i);
// only animate the views not being added or removed
if (child != newView) {
setupChangeAnimation(parent, changeReason, baseAnimator, duration, child);
}
}
if (mAnimateParentHierarchy) {
Animator parentAnimator = (changeReason == APPEARING) ?
defaultChangeIn : defaultChangeOut;
ViewGroup tempParent = parent;
while (tempParent != null) {
ViewParent parentParent = tempParent.getParent();
if (parentParent instanceof ViewGroup) {
setupChangeAnimation((ViewGroup)parentParent, changeReason, parentAnimator,
duration, tempParent);
tempParent = (ViewGroup) parentParent;
} else {
tempParent = null;
}
}
}
// This is the cleanup step. When we get this rendering event, we know that all of
// the appropriate animations have been set up and run. Now we can clear out the
// layout listeners.
observer.addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
public boolean onPreDraw() {
parent.getViewTreeObserver().removeOnPreDrawListener(this);
int count = layoutChangeListenerMap.size();
if (count > 0) {
Collection<View> views = layoutChangeListenerMap.keySet();
for (View view : views) {
View.OnLayoutChangeListener listener = layoutChangeListenerMap.get(view);
view.removeOnLayoutChangeListener(listener);
}
}
layoutChangeListenerMap.clear();
return true;
}
});
}
/**
* This flag controls whether CHANGE_APPEARING or CHANGE_DISAPPEARING animations will
* cause the default changing animation to be run on the parent hierarchy as well. This allows
* containers of transitioning views to also transition, which may be necessary in situations
* where the containers bounds change between the before/after states and may clip their
* children during the transition animations. For example, layouts with wrap_content will
* adjust their bounds according to the dimensions of their children.
*
* <p>The default changing transitions animate the bounds and scroll positions of the
* target views. These are the animations that will run on the parent hierarchy, not
* the custom animations that happen to be set on the transition. This allows custom
* behavior for the children of the transitioning container, but uses standard behavior
* of resizing/rescrolling on any changing parents.
*
* @param animateParentHierarchy A boolean value indicating whether the parents of
* transitioning views should also be animated during the transition. Default value is true.
*/
public void setAnimateParentHierarchy(boolean animateParentHierarchy) {
mAnimateParentHierarchy = animateParentHierarchy;
}
/**
* Utility function called by runChangingTransition for both the children and the parent
* hierarchy.
*/
private void setupChangeAnimation(final ViewGroup parent, final int changeReason,
Animator baseAnimator, final long duration, final View child) {
// If we already have a listener for this child, then we've already set up the
// changing animation we need. Multiple calls for a child may occur when several
// add/remove operations are run at once on a container; each one will trigger
// changes for the existing children in the container.
if (layoutChangeListenerMap.get(child) != null) {
return;
}
// Make a copy of the appropriate animation
final Animator anim = baseAnimator.clone();
// Set the target object for the animation
anim.setTarget(child);
// A ObjectAnimator (or AnimatorSet of them) can extract start values from
// its target object
anim.setupStartValues();
// If there's an animation running on this view already, cancel it
Animator currentAnimation = pendingAnimations.get(child);
if (currentAnimation != null) {
currentAnimation.cancel();
pendingAnimations.remove(child);
}
// Cache the animation in case we need to cancel it later
pendingAnimations.put(child, anim);
// For the animations which don't get started, we have to have a means of
// removing them from the cache, lest we leak them and their target objects.
// We run an animator for the default duration+100 (an arbitrary time, but one
// which should far surpass the delay between setting them up here and
// handling layout events which start them.
ValueAnimator pendingAnimRemover = ValueAnimator.ofFloat(0f, 1f).
setDuration(duration + 100);
pendingAnimRemover.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator animation) {
pendingAnimations.remove(child);
}
});
pendingAnimRemover.start();
// Add a listener to track layout changes on this view. If we don't get a callback,
// then there's nothing to animate.
final View.OnLayoutChangeListener listener = new View.OnLayoutChangeListener() {
public void onLayoutChange(View v, int left, int top, int right, int bottom,
int oldLeft, int oldTop, int oldRight, int oldBottom) {
// Tell the animation to extract end values from the changed object
anim.setupEndValues();
if (anim instanceof ValueAnimator) {
boolean valuesDiffer = false;
ValueAnimator valueAnim = (ValueAnimator)anim;
PropertyValuesHolder[] oldValues = valueAnim.getValues();
for (int i = 0; i < oldValues.length; ++i) {
PropertyValuesHolder pvh = oldValues[i];
KeyframeSet keyframeSet = pvh.mKeyframeSet;
if (keyframeSet.mFirstKeyframe == null ||
keyframeSet.mLastKeyframe == null ||
!keyframeSet.mFirstKeyframe.getValue().equals(
keyframeSet.mLastKeyframe.getValue())) {
valuesDiffer = true;
}
}
if (!valuesDiffer) {
return;
}
}
long startDelay;
if (changeReason == APPEARING) {
startDelay = mChangingAppearingDelay + staggerDelay;
staggerDelay += mChangingAppearingStagger;
} else {
startDelay = mChangingDisappearingDelay + staggerDelay;
staggerDelay += mChangingDisappearingStagger;
}
anim.setStartDelay(startDelay);
anim.setDuration(duration);
Animator prevAnimation = currentChangingAnimations.get(child);
if (prevAnimation != null) {
prevAnimation.cancel();
}
Animator pendingAnimation = pendingAnimations.get(child);
if (pendingAnimation != null) {
pendingAnimations.remove(child);
}
// Cache the animation in case we need to cancel it later
currentChangingAnimations.put(child, anim);
parent.requestTransitionStart(LayoutTransition.this);
// this only removes listeners whose views changed - must clear the
// other listeners later
child.removeOnLayoutChangeListener(this);
layoutChangeListenerMap.remove(child);
}
};
// Remove the animation from the cache when it ends
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationStart(Animator animator) {
if (mListeners != null) {
for (TransitionListener listener : mListeners) {
listener.startTransition(LayoutTransition.this, parent, child,
changeReason == APPEARING ?
CHANGE_APPEARING : CHANGE_DISAPPEARING);
}
}
}
@Override
public void onAnimationCancel(Animator animator) {
child.removeOnLayoutChangeListener(listener);
layoutChangeListenerMap.remove(child);
}
@Override
public void onAnimationEnd(Animator animator) {
currentChangingAnimations.remove(child);
if (mListeners != null) {
for (TransitionListener listener : mListeners) {
listener.endTransition(LayoutTransition.this, parent, child,
changeReason == APPEARING ?
CHANGE_APPEARING : CHANGE_DISAPPEARING);
}
}
}
});
child.addOnLayoutChangeListener(listener);
// cache the listener for later removal
layoutChangeListenerMap.put(child, listener);
}
/**
* Starts the animations set up for a CHANGING transition. We separate the setup of these
* animations from actually starting them, to avoid side-effects that starting the animations
* may have on the properties of the affected objects. After setup, we tell the affected parent
* that this transition should be started. The parent informs its ViewAncestor, which then
* starts the transition after the current layout/measurement phase, just prior to drawing
* the view hierarchy.
*
* @hide
*/
public void startChangingAnimations() {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentChangingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
if (anim instanceof ObjectAnimator) {
((ObjectAnimator) anim).setCurrentPlayTime(0);
}
anim.start();
}
}
/**
* Ends the animations that are set up for a CHANGING transition. This is a variant of
* startChangingAnimations() which is called when the window the transition is playing in
* is not visible. We need to make sure the animations put their targets in their end states
* and that the transition finishes to remove any mid-process state (such as isRunning()).
*
* @hide
*/
public void endChangingAnimations() {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentChangingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.start();
anim.end();
}
}
/**
* Returns true if animations are running which animate layout-related properties. This
* essentially means that either CHANGE_APPEARING or CHANGE_DISAPPEARING animations
* are running, since these animations operate on layout-related properties.
*
* @return true if CHANGE_APPEARING or CHANGE_DISAPPEARING animations are currently
* running.
*/
public boolean isChangingLayout() {
return (currentChangingAnimations.size() > 0);
}
/**
* Returns true if any of the animations in this transition are currently running.
*
* @return true if any animations in the transition are running.
*/
public boolean isRunning() {
return (currentChangingAnimations.size() > 0 || currentAppearingAnimations.size() > 0 ||
currentDisappearingAnimations.size() > 0);
}
/**
* Cancels the currently running transition. Note that we cancel() the changing animations
* but end() the visibility animations. This is because this method is currently called
* in the context of starting a new transition, so we want to move things from their mid-
* transition positions, but we want them to have their end-transition visibility.
*
* @hide
*/
public void cancel() {
if (currentChangingAnimations.size() > 0) {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentChangingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.cancel();
}
currentChangingAnimations.clear();
}
if (currentAppearingAnimations.size() > 0) {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentAppearingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.end();
}
currentAppearingAnimations.clear();
}
if (currentDisappearingAnimations.size() > 0) {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentDisappearingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.end();
}
currentDisappearingAnimations.clear();
}
}
/**
* Cancels the specified type of transition. Note that we cancel() the changing animations
* but end() the visibility animations. This is because this method is currently called
* in the context of starting a new transition, so we want to move things from their mid-
* transition positions, but we want them to have their end-transition visibility.
*
* @hide
*/
public void cancel(int transitionType) {
switch (transitionType) {
case CHANGE_APPEARING:
case CHANGE_DISAPPEARING:
if (currentChangingAnimations.size() > 0) {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentChangingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.cancel();
}
currentChangingAnimations.clear();
}
break;
case APPEARING:
if (currentAppearingAnimations.size() > 0) {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentAppearingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.end();
}
currentAppearingAnimations.clear();
}
break;
case DISAPPEARING:
if (currentDisappearingAnimations.size() > 0) {
LinkedHashMap<View, Animator> currentAnimCopy =
(LinkedHashMap<View, Animator>) currentDisappearingAnimations.clone();
for (Animator anim : currentAnimCopy.values()) {
anim.end();
}
currentDisappearingAnimations.clear();
}
break;
}
}
/**
* This method runs the animation that makes an added item appear.
*
* @param parent The ViewGroup to which the View is being added.
* @param child The View being added to the ViewGroup.
*/
private void runAppearingTransition(final ViewGroup parent, final View child) {
Animator currentAnimation = currentDisappearingAnimations.get(child);
if (currentAnimation != null) {
currentAnimation.cancel();
}
if (mAppearingAnim == null) {
if (mListeners != null) {
for (TransitionListener listener : mListeners) {
listener.endTransition(LayoutTransition.this, parent, child, APPEARING);
}
}
return;
}
Animator anim = mAppearingAnim.clone();
anim.setTarget(child);
anim.setStartDelay(mAppearingDelay);
anim.setDuration(mAppearingDuration);
if (anim instanceof ObjectAnimator) {
((ObjectAnimator) anim).setCurrentPlayTime(0);
}
if (mListeners != null) {
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator anim) {
currentAppearingAnimations.remove(child);
for (TransitionListener listener : mListeners) {
listener.endTransition(LayoutTransition.this, parent, child, APPEARING);
}
}
});
}
currentAppearingAnimations.put(child, anim);
anim.start();
}
/**
* This method runs the animation that makes a removed item disappear.
*
* @param parent The ViewGroup from which the View is being removed.
* @param child The View being removed from the ViewGroup.
*/
private void runDisappearingTransition(final ViewGroup parent, final View child) {
Animator currentAnimation = currentAppearingAnimations.get(child);
if (currentAnimation != null) {
currentAnimation.cancel();
}
if (mDisappearingAnim == null) {
if (mListeners != null) {
for (TransitionListener listener : mListeners) {
listener.endTransition(LayoutTransition.this, parent, child, DISAPPEARING);
}
}
return;
}
Animator anim = mDisappearingAnim.clone();
anim.setStartDelay(mDisappearingDelay);
anim.setDuration(mDisappearingDuration);
anim.setTarget(child);
if (mListeners != null) {
anim.addListener(new AnimatorListenerAdapter() {
@Override
public void onAnimationEnd(Animator anim) {
currentDisappearingAnimations.remove(child);
for (TransitionListener listener : mListeners) {
listener.endTransition(LayoutTransition.this, parent, child, DISAPPEARING);
}
}
});
}
if (anim instanceof ObjectAnimator) {
((ObjectAnimator) anim).setCurrentPlayTime(0);
}
currentDisappearingAnimations.put(child, anim);
anim.start();
}
/**
* This method is called by ViewGroup when a child view is about to be added to the
* container. This callback starts the process of a transition; we grab the starting
* values, listen for changes to all of the children of the container, and start appropriate
* animations.
*
* @param parent The ViewGroup to which the View is being added.
* @param child The View being added to the ViewGroup.
*/
public void addChild(ViewGroup parent, View child) {
// Want disappearing animations to finish up before proceeding
cancel(DISAPPEARING);
// Also, cancel changing animations so that we start fresh ones from current locations
cancel(CHANGE_APPEARING);
if (mListeners != null) {
for (TransitionListener listener : mListeners) {
listener.startTransition(this, parent, child, APPEARING);
}
}
runChangeTransition(parent, child, APPEARING);
runAppearingTransition(parent, child);
}
/**
* This method is called by ViewGroup when a child view is about to be added to the
* container. This callback starts the process of a transition; we grab the starting
* values, listen for changes to all of the children of the container, and start appropriate
* animations.
*
* @param parent The ViewGroup to which the View is being added.
* @param child The View being added to the ViewGroup.
*/
public void showChild(ViewGroup parent, View child) {
addChild(parent, child);
}
/**
* This method is called by ViewGroup when a child view is about to be removed from the
* container. This callback starts the process of a transition; we grab the starting
* values, listen for changes to all of the children of the container, and start appropriate
* animations.
*
* @param parent The ViewGroup from which the View is being removed.
* @param child The View being removed from the ViewGroup.
*/
public void removeChild(ViewGroup parent, View child) {
// Want appearing animations to finish up before proceeding
cancel(APPEARING);
// Also, cancel changing animations so that we start fresh ones from current locations
cancel(CHANGE_DISAPPEARING);
if (mListeners != null) {
for (TransitionListener listener : mListeners) {
listener.startTransition(this, parent, child, DISAPPEARING);
}
}
runChangeTransition(parent, child, DISAPPEARING);
runDisappearingTransition(parent, child);
}
/**
* This method is called by ViewGroup when a child view is about to be removed from the
* container. This callback starts the process of a transition; we grab the starting
* values, listen for changes to all of the children of the container, and start appropriate
* animations.
*
* @param parent The ViewGroup from which the View is being removed.
* @param child The View being removed from the ViewGroup.
*/
public void hideChild(ViewGroup parent, View child) {
removeChild(parent, child);
}
/**
* Add a listener that will be called when the bounds of the view change due to
* layout processing.
*
* @param listener The listener that will be called when layout bounds change.
*/
public void addTransitionListener(TransitionListener listener) {
if (mListeners == null) {
mListeners = new ArrayList<TransitionListener>();
}
mListeners.add(listener);
}
/**
* Remove a listener for layout changes.
*
* @param listener The listener for layout bounds change.
*/
public void removeTransitionListener(TransitionListener listener) {
if (mListeners == null) {
return;
}
mListeners.remove(listener);
}
/**
* Gets the current list of listeners for layout changes.
* @return
*/
public List<TransitionListener> getTransitionListeners() {
return mListeners;
}
/**
* This interface is used for listening to starting and ending events for transitions.
*/
public interface TransitionListener {
/**
* This event is sent to listeners when any type of transition animation begins.
*
* @param transition The LayoutTransition sending out the event.
* @param container The ViewGroup on which the transition is playing.
* @param view The View object being affected by the transition animation.
* @param transitionType The type of transition that is beginning,
* {@link android.animation.LayoutTransition#APPEARING},
* {@link android.animation.LayoutTransition#DISAPPEARING},
* {@link android.animation.LayoutTransition#CHANGE_APPEARING}, or
* {@link android.animation.LayoutTransition#CHANGE_DISAPPEARING}.
*/
public void startTransition(LayoutTransition transition, ViewGroup container,
View view, int transitionType);
/**
* This event is sent to listeners when any type of transition animation ends.
*
* @param transition The LayoutTransition sending out the event.
* @param container The ViewGroup on which the transition is playing.
* @param view The View object being affected by the transition animation.
* @param transitionType The type of transition that is ending,
* {@link android.animation.LayoutTransition#APPEARING},
* {@link android.animation.LayoutTransition#DISAPPEARING},
* {@link android.animation.LayoutTransition#CHANGE_APPEARING}, or
* {@link android.animation.LayoutTransition#CHANGE_DISAPPEARING}.
*/
public void endTransition(LayoutTransition transition, ViewGroup container,
View view, int transitionType);
}
}